Distribuição de nematoides parasitas de bananeira no estado da Bahia, agressividade de populações e prevalência de espécies

Abstract

Among the parasitic species of nematodes in plants, the main ones in bananas are Radopholus similis, Helicotylenchus multicinctus, Pratylenchus coffeae, Meloidogyne spp. and Rotylenchulus reniformis. The state of Bahia is one of the main banana producers in Brazil and the county of Bom Jesus da Lapa is considered the largest. The objective of the present work was to investigate the distribution of parasitic nematodes in bananas in the State and estimate levels of aggressiveness of the populations sampled as well as their prevalence in the region. One-hundred and forty-seven combined soil samples in 36 counties, representative of the 9 regions, were collected. Approximately 65% of the samples were carried out in the rhizosphere of cultivars of the Prata Subgroup (AAB), followed by Cavendish (22%) and Plantains (10%) and the remaining from the Silk and Pisang Mas cultivars. The H. multicinctus species was predominant in 87.1 % of the samples, R. reniformis in 63.3%, Meloidogyne spp. in 61.9%, Pratylenchus spp. in 2.7% and R. similis in 2.0% of the sampled areas. Enzymatic analysis estimated prevalence of M. incognita in 41.5% of the samples followed by M. arenaria and M. javanica in 36.6% and 18.3% in the populations analyzed, respectively. Considering the reproduction factor, there was no significant difference in the aggressiveness between the populations of M. incognita. However, there was difference in the reproductive capacity between the thirteen nematode populations analyzed, whereas the population from Bom Jesus da Lapa (Bahia) presented highest multiplication rate. This population has potential for use aiming the selection of sources of resistance to M. incognita for use in the banana genetic breeding program. In an external sample carried out at the county of Jaíba, Minas Gerais State, characteristic symptoms of the infection by rootrot–nematodes (Meloidogyne enterolobii), was observed. Morphological, morphometric and isoenzymatic characterizations as well as pathogenicity tests which confirm the species were also carried out. This is the first report of Meloidogyne enterolobii in bananas in Brazil.